ABANDONED. YA Nonfiction Epidemic, Boy's shadow or clone follows him around, blueish cover, something including a mirror or glass

[Ella]

This YA fiction book is older, probably from the 90s or early 2000s the cover was blue with the outline of a boy coming out of a mirror I think, the book was about a town that had a serious disease epidemic, I think the boy had an uncle that was involved but for the most part there weren't a lot of characters, he was being followed by his shadow or clone or something but it was malicious, I think it had something to do with a mirror as well

[Kym]

The Empty Mirror by James Lincoln Collier?

[Rainbowheart]

Still looking, Ella?

[Kris]

No response, moving to Abandoned folder.

Ella (OP) was last active on the site in May 2018.